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A semi-commercial scale experiment was conducted to evaluate the effect of irrigation frequency on the growth of red earthworms (Eisenia spp.) and the chemical properties of the resulting vermicompost. The experiment was conducted in Zulia state, Venezuela. Frequency of irrigation tested were none (N), once (O) or twice (T) a week. Earthworms (2000/m2) were deposited in 1-m2 concrete containers (199.0 ± 0.39 mg/earthworm). The N containers were covered to avoid water loss. Each container was considered an experimental unit. Bovine manure (0.15m3) was used as substrate. At the beginning of the trial, all treatments received 24 L of water. Biomass was measured every 24 days, and the first 40 earthworms found in the top of each container were weighed. Cocoon production was determined at 42 days by counting cocoons that were found in five 240 cm3 sub-samples of substrate. Final biomass was determined at day 92, weighing all earthworms located in two quarters of each container. Vermicompost was chemically characterized for OM, P, K, Ca, Mg, Zn, Fe, Mn, and Cu concentrations and pH and electrical conductivity were measured. Humidity of the substrate was established every 21 days through a gravimetric method. A completely randomized design with 5 observations per treatment was used. Statistical differences were established for biomass at day 84, with the heaviest earthworms observed in N (193.26 ± 0.22 mg/earthworm) and the lightest in O (111.05 ± 8.77 mg/earthworm). Cocoon production differed (P < 0.05) between T (69.2 ± 0.03 cocoons/240 cm3) and O (33.4 ± 4.86 cocoons/240 cm3), whereas N was similar to the others treatments (48.9 ± 1.41 cocoons/240 cm3). No differences were established for final earthworm biomass and the chemical characteristics of vermicompost. Frequency of irrigation affected biomass and cocoon production of red earthworms. It is suggested that covering the containers is a practical management practice to supply sufficient humidity under hot conditions to obtain adequate earthworm performance. Collateral benefits include reduction of labor required for irrigation activities. [ABSTRACT FROM AUTHOR]